Merck files Keytruda for lung cancer, eyes first-line niche

Merck announced Sunday that it filed its immuno-oncology drug Keytruda with the FDA as a second-line treatment for lung cancer. If approved, Keytruda will be the second immuno-oncology drug to reach the US market behind Bristol-Myers Squibb's Opdivo, which was approved in March, also for a second-line indication.

While BMS enjoys a head start, Merck presented new data that could prove beneficial in the first-line, or treatment-naive, setting, possibly carving out a fruitful niche for the company in the category. The data revealed that 19.4% of patients taking Keytruda saw their tumors shrink. That stacks up well against Opdivo—which reported a 15% overall response rate in trials for non-small-cell lung carcinoma.

Merck has not yet reported the overall survival numbers, which may be the crucial data set in separating these two treatments. Leerink Partners analyst Seamus Fernandez wrote in an investor note that Keytruda's “lack of randomized survival data is likely to be a disadvantage” when compared to Opdivo, at least until Merck releases more information.

Merck may have found an advantage in its sub-group data, though. The drugmaker reported that patients whose tumors had the highest expression of a genetic protein, PD-L1, fared significantly better than patients with a lesser expression of the protein. About 45% of patients in the high PD-L1 group saw their tumors shrink, compared to 16.5% and 10.7%, respectively, in the intermediate and low-expressing segments.

Researchers found similar results when measuring progression-free survival. The high PD-L1 group had 6.3 months of progression-free survival, compared to 3.3 months and 2.3 months in the intermediate and low PD-L1 groups.

Fernandez, citing key opinion leaders, believes this biomarker will have little bearing in the second- or third-line setting, but it could have a greater role in the future as a way to “direct, not select” patients for treatments. “KOLs continue to emphasize a stronger interest in broader early access that does not rely on a PD-L1 biomarker to select patients for a second- or third- line treatment,” he said, “As PD1/PD-L1 therapy advances into [first-line] treatment, they expect the PD-L1 biomarker to play a larger role. “

Merck also noted in its submission announcement that Dako had filed a pre-market authorization application for a PD-L1 companion diagnostic.